Controlling pest populations is essential to human health, modern agriculture, food storage, and hygiene. There are more than ten thousand species of pests that cause losses in agriculture and the worldwide agricultural losses amount to billions of U.S. dollars each year. Accordingly, there exists a continuous need for new pesticides and for methods of producing and using such pesticides.
The Insecticide Resistance Action Committee (IRAC) has classified insecticides into categories based on the best available evidence of the mode of action of such insecticides. Insecticides in the IRAC Mode of Action Group 5 are nicotinic acetylcholine receptor (nAChR) allosteric activators, such as spinosyns compounds. The insecticides in this class are believed to cause hyperexcitation of the nervous system of the affected insects. Acetylcholine has been reported as the major excitatory neurotransmitter in the insect central nervous system. Examples of insecticides in this class are spinetoram and spinosad.
Spinetoram is a mixture of 3′-O-ethyl-5,6-dihydro spinosyn J and 3′-O-ethyl spinosyn L. 3′-O-ethyl-5,6-dihydro spinosyn J is (2R,3aR,5aR,5bS,9S,13S,14R,16aS,16bR)-2-(6-deoxy-3-O-ethyl-2,4-di-O-methyl-α-L-mannopyranosyloxy)-13-[(2R,5S,6R)-5-(dimethylamino) tetrahydro-6-methylpyran-2-yloxy]-9-ethyl-2,3,3a,4,5,5a,5b,6,9,10,11,12,13,14,16a,16b-hexadeca hydro-14-methyl-1H-as-indaceno[3,2-d]oxacyclododecine-7,15-dione. 3′-O-ethyl spinosyn L is (2R,3aR,5aS,5bS,9S,13S,14R,16aS,16bS)-2-[(6-deoxy-3-O-ethyl-2,4-di-O-methyl-α-L-manno pyranosyl)oxy]-13-[[(2R,5S,6R)-5-(dimethylamino)tetrahydro-6-methyl-2H-pyran-2-yl]oxy]-9-ethyl-2,3,3a,5a,5b,6,9,10,11,12,13,14,16a,16b-tetradecahydro-4,14-dimethyl-1H-asindaceno[3,2-d] oxacyclododecin-7,15-dione.
Spinosad is a mixture of spinosyn A and spinosyn D. Spinosyn A is 2-((6-deoxy-2,3,4-tri-O-methyl-a-L-mannopyranosyl)oxy)-13-(((5-dimethylamino)tetrahydro-6-methyl-2H-pyran-2-yl)oxy)-9-ethyl-2,3,3a,5a,5b,6,9,10,11,12,13,14,16a,16b-tetradecahydro-14-methyl-1H-asindaceno(3,2-d)oxacyclododecin-7,15-dione. Spinosyn B is 2-((6-deoxy-2,3,4-tri-O-methyl-a-Lmannopyranosyl)oxy)-13-(((5-dimethylamino)tetrahydro-6-methyl-2H-pyran-2-yl)oxy)-9-ethyl-2,3,3a,5a,5b,6,9,10,11,12,13,14,16a,16b-tetradecahydro-4,14-dimethyl-1H-asindaceno(3,2-d)oxacyclododecin-7,15-dione.
Although the rotational application of pesticides having different modes of action may be adopted for good pest management practice, this approach does not necessarily give satisfactory pest control. Furthermore, even though combinations of pests have been studied, a high synergistic action has not always been found.